The government was widely criticised for its response to the devastating blazes -- including Prime Minister Scott Morrison who holidayed in Hawaii at the heigh of the crisis -- and announced the national inquiry in February.

The Royal Commission -- tasked with finding ways to improve how Australia deals with natural disasters -- heard from a leading government scientist that last summer was not a "one-off event".

The Bureau of Meteorology's head of climate monitoring, Karl Braganza, said a prolonged drought was one of the key factors that led to the dangerous fires.

However, Braganza emphasised that the recent bushfires were part of an underlying climate trend, which has emerged this century and "really challenged what we thought fire weather looked like preceding this period".

"This isn't a one-off event that we're looking at here," he said. "The frequency of these events, if you look at the historical record, seems to be increasing."

"These large fire events, when you look back over the 19th and 20th century, were not as frequent as they were this century."

Scientists say global warming is lengthening the country's summers and making them increasingly dangerous, with shorter winters making it more difficult to carry out bushfire prevention work.

More than 30 people died and thousands of homes were destroyed during the blazes in late 2019-early 2020, leaving local communities devastated. Some victims are still living in tents as the southern hemisphere winter approaches.

An estimated one billion animals perished as more than 20 percent of Australia's forests burned in one of the worst bushfire seasons on record.

Australia has seen dozens of inquests into the causes of bushfires and steps that could be taken to mitigate them. But many measures recommended by inquiries going back to the 1930s have still not been implemented.

The inquiry is required to report its findings by August 31 ahead of the next bushfire season.